Depending upon retention settings in your environment, you may fetch the alerts directly from database by using below query
SELECT * FROM [CA_UIM].[dbo].[NAS_TRANSACTION_SUMMARY] where nimts < getdate()-60 and nimts > getdate()-90
Please modify according to your db name and duration, you can even fetch few columns only depending on your need and export result to csv.
Secondly, you may use CABI/unified reporter for setting up a report like that using the same table.